The program is divided into two sections-basic research and clinical research-designed to investigate neurobiological processes that are considered to be relevant to the understand of major psychiatric disorders. The section dealing with basic research consits of a continuation of ongoing studied on cetral neurotransmitters, receptors, and durgs and a second part addresses itself to nerrobiological processes in behavior. The clinical research consits of studies directed toward an increase of our understanding of biological processes that may be relevant to the genesis of specific psychopathological states and clinical investigations of biological processes that will affect diagnosis and treatment in the hospital setting. BIBLIOGRAPHIC REFERENCES: Aghajanian, G.K., and Gallager, D.W. Raphe origin of serotonergic nerves terminating in the cerebral ventricles. Brain Res., 88: 221-231, 1975. Gallager, D.W. and Aghajania, G.K. Inhibition of firing of raphe neurons by tryptophan and 5-hydroxytryptopan: Blockade by inhibiting serotonin synthesis with R04-4602 Neuropharmacol., in press, 1976.